This proposal is submitted in response to the RFA: DK-93-07, "NIDDM primary Prevention Trial" NIDDM is a major public health problem in the United States and its prevalence is disproportionately high among a number of minority groups including Native American, Hispanics and African-Americans, Members of these minority groups, obese subjects, persons with a family history of NIDDM among first degree relatives and women with prior gestational diabetes mellitus (GDM) of all racial and ethic groups are at high risk for the development of NIDDM. We have developed a protocol for a multicenter study to test the hypothesis that the appearance of NIDDM can be delayed or prevented by life style or pharmacological intervention in women with prior GDM or in subjects at high risk for NIDDM who presently have impaired glucose tolerance (IGT). We propose to compare the rate of progression of IGT to NIDDM and mild NIDDM to NIDDM with fasting hyperglycemia in groups receiving intensive life-style intervention with diet, (low fat moderated fiber reduced calorie) and exercise (supervise instruction and maintenance of physical fitness) or drug treatment (sulfonylurea oral hypoglycemic agent or an anorectic agent) with conventional advice regarding diet and exercise. We propose that subjects with prior GDM represent half of the women recruited for the study and that the total population enrolled include 20 percent Hispanics, 20 percent African-American, 10 percent native Americans and 50 percent Caucasians and members of other minorities. We have identified a large population of women with previous GDM that includes approximately equal numbers of Black, hispanic and White women and are prepared to serve as a center for a concentrated subgroup enrollment of such subjects. We are also prepared to recruit Hispanic, African- American and White subjects from the general population who are at high risk for IGT. Our study investigators have extensive experience in the care of patients with diabetes mellitus, have broad and in depth experience in collaborative diabetes related and cardiovascular disease related clinical and epidemiological studies. These projects have provided extensive experience in recruitment and retention of minority subjects including women with prior GDM. The project investigators are prepared to collaborate and cooperate in the final design of the study protocol by the steering committee as well as implement it with enthusiasm and to the best of our collective abilities.